A non-interactive zero-knowledge authentication is known as a protocol for verifying knowledge of the answer to a question. Combination of the non-interactive zero-knowledge and public key cryptography allows decryption of a ciphertext after verifying the validity of the ciphertext. This can increase the security of the public key cryptography.
The non-interactive zero-knowledge authentication combined with the public key cryptography, however, is disadvantageous not only in that more computational cost is required for encryption and decryption but also in that ciphertexts become longer.